Analytical Unsteady aerodynamics model of a Horizontal axis wind turbines due to linear change in wind speed

Abstract

Small wind turbines use MPPT (Maximum power point Tracking) algorithm that depends on the performance relation developed using a steady BEM [Blade Element Momentum] code. However, small wind turbines work under harsh unsteady environment that is subjected to large fluctuation in wind and rotor speeds. This will lead to unsteady power generated that differ significantly from the one predicted using steady codes. In this work, a semi-empirical model is developed that correlates an unsteady physical variable, like the unsteady stream line length, to a measurable variable in unsteady operation, like tip speed ratio. This model use the unsteady Euler equation supplied with a measured data of power coefficient and wind speed of a 5 kW wind turbine. The analysis shows that the stream line length shows some correlation with tip speed ratio. Further data analysis is currently underway to investigate this correlation and further results will be reported in the final presentation.